Shock absorbing air cushions



Jan. 14, 1964 A. E. GILLMORE 3,117,752

sHocK ABSORBING AIR CUSHIONS Filed Dec. 26. 1961 INVENTOR ALFRED E. GILLMORE ATTORNEYS United States Patent 3,117,752 SHOCK ABSORBIN G AIR CUSHIONS Alfred Edward Gillmore, Woking, Surrey, England, as-

signor to G. Q. Parachute Company Limited, Woking, England, a British company Filed Dec. 26, 1961, Ser. No. 161,981 7 Claims. (Cl. 244-138) This invention relates to shock-absorbing devices for loads falling to the ground and more particularly for stores and equipment dropped by parachute from the air, said device including an air-cushion which is intended to reduce the liability to damage at the landing of the load.

These cusions have usually been made of substantially air-impervious fabric with vents to allow the relief of internal pressure on landing, the intention being that the cushion should remain in a vertical position during defiation. In actual practice, the air cushion is very often deflected sideways out of its vertical disposition by the drag of the parachute after the base of the cushion has made contact with the ground. This sideways drag or drift is liable to cause the air-cushion to burst instead of becoming deflated at a speed controlled by the vents.

According to one aspect, the present invention consists in a shock-absorbing device which includes at least one air-cushion, a load-carrying platform, a skid-pan, said aircushion being disposed between said platform and said skid-pan, and means linking said platform and said skidpan together to limit the extent to which, and to control the manner in which, the platform can swing out of vertical alignment with said skid-pan.

The skid-pan may be made with upturned or bevelled edges so as to enable it to slide readily over the ground with which it makes contact upon landing. Any increase in the ability of the skid-pan to slide over the ground will assist in the maintenance of vertical alignment of the platform and skid-pan.

The present invention will now be more particularly described with reference to the accompanying drawing which illustrates a load-carrying platform 1, and a skidpan 2, both of which are of rectangular shape in plan and of substantially the same area. Four cylindrical aircushions 3, 4, 5 and 6 are disposed between the platform 1, and the skid-pan 2, each air-cushion being provided with vent means for facilitating gradual deflation thereof. The corner 7 of the platform 1 is connected to points at or adjacent to diagonally opposite corners 8 and 9 of the skid-pan 2 by connecting means, which may be, for example, steel cables 10 and 11. The same applies to each of the corners 12, 13 and 14 of the platform 1 and the skidpan 2 to which, for example, steel cables 15, 16, 17, 18, 19 and 20 are connected. In this manner a pair of crossed cables connects together corresponding corners of the platform and skid-pan.

At the end of a parachute-descent of a load, the skid pan 2 makes contact with the ground, the load on the platform 1 will be subjected to deceleration under the infiuence of the controlled rate of deflation of the aircushions 3, 4, 5 and 6. In the event of a tendency of the suspended load to drift sideways the load on the platform will be constrained to follow a downwardly curved path determined by the parallel-motion device which consists of a pair of parallel cables contained in a single inclined plane (for example, the cables 15, 18 or the cables 3,l 17,752 Patented Jan. 14, 1964 1 1, 16). In this manner the impact shock on landing is absorbed before the air-cushions can be deflected sufficiently from their normal vertical or substantially vertical disposition between the platform 1 and skid-pan 2 to cause them to burst.

The several air-cushions illustrated in the drawing may be replaced by a single air-cushion constructed, for example, as described and illustrated in United Kingdom Patent Specification No. 777,495.

The skid-pan 2 may take the form either of a dish having an upturned, canted rim or of a block having bevelled edges.

What I claim as my invention and desire to secure b Letters Patent of the United States is:

l. A device comprising a skid-pan, a load carrying platform spaced from and above the skid-pan, said platform having a plurality of upper points thereon arranged to enclose a central area of said platform, said skid-pan having a plurality of lower points arranged thereon so as to enclose a central area of said skid-pan and said lower points being equal in number to the number of upper points, each lower point being substantially in vertical alignment with an upper point, a pair of flexible and substantially non-stretchable elongated stays extending diagonally and divergingly from each lower point on said skidpan to the pair of points on said platform which are directly above the pair of points on said skid-pan adjacent to the point on said skid-pan from which the pair of stays extend whereby the number of said stays equals the total number of said upper and lower points and the stays extending from each of said lower points crosses the stays extending from two adjacent lower points, securing means fixedly securing the ends of said stays to said platform and skid-pan at one of said upper points and one of said lower points, shock absorbing means extending between said central areas of said platform and said skid-pan, said shock absorbing means being completely surrounded by and enclosed by said stays, said points being arranged so that each of said stays forms a relatively small angle with said platform.

2. A device comprising a skid-pan, a load carrying platform spaced from and above the skid-pan, said platform having a plurality of upper points thereon arranged to enclose a central area of said platform, said skid-pan having a plurality of lower points arranged thereon so as to enclose a central area of said skid-pan and said lower points being equal in number to the number of upper points, each lower point being substantially in vertical alignment with an upper point, a pair of flexible and substantiall non-stretchable elongated stays extending diagonally and divergingly from each lower point on said skidpan to a pair of points on said platform whereby the number of said stays equals the total number of said upper and lower points and the stays extending from each of said lower points cross two stays extending from two adjacent lower points, securing means fixably securing the ends of said stays to said platform and skid-pan at one of said upper and one of said lower points, shock absorbing means extending between said central areas of said platform and said skid-pan, said shock absorbing means being completely surrounded by and enclosed by said stays, said points being arranged so that each of said stays forms a relatively small angle with said platform.

3. A device as defined in claim 2, wherein said angle is less than 45.

4. A device as defined in claim 3, including peripheral edges on said skid-pan which slope upwardly and outwardly from the bottom thereof so as to reduce the resistance of said device when sliding on a surface.

5. A device as defined in claim 4, wherein said stays total eight in number and said points are arranged to enclose central areas of square shape.

6. A device as defined in claim 4, wherein said skid-pan and said platform each comprises a fiat imperforate square plate, saidcentral areas being of square shape and having their sides parallel to the sides of the square plates whereby said points are located in the corners of said square plates.

7. A device as defined in claim 6, wherein said shock absorbing means comprises four spaced and vertically extending air cushions, each cushion located in corners of said square central areas.

References Cited in the file of this patent UNITED STATES PATENTS 200,283 Haasz Feb. 12, 1878 2,713,466 Fletcher et al. July 19, 1955 2,725,578 Keller Dec. 6, 1955 FOREIGN PATENTS 829,401 Great Britain Mar. 2, 1960 1,234,194 France May 16, 1960 

1. A DEVICE COMPRISING A SKID-PAN, A LOAD CARRYING PLATFORM SPACED FROM AND ABOVE THE SKID-PAN, SAID PLATFORM HAVING A PLURALITY OF UPPER POINTS THEREON ARRANGED TO ENCLOSE A CENTRAL AREA OF SAID PLATFORM, SAID SKID-PAN HAVING A PLURALITY OF LOWER POINTS ARRANGED THEREON SO AS TO ENCLOSE A CENTRAL AREA OF SAID SKID-PAN AND SAID LOWER POINTS BEING EQUAL IN NUMBER TO THE NUMBER OF UPPER POINTS, EACH LOWER POINT BEING SUBSTANTIALLY IN VERTICAL ALIGNMENT WITH AN UPPER POINT, A PAIR OF FLEXIBLE AND SUBSTANTIALLY NON-STRETCHABLE ELONGATED STAYS EXTENDING DIAGONALLY AND DIVERGINGLY FROM EACH LOWER POINT ON SAID SKIDPAN TO THE PAIR OF POINTS ON SAID PLATFORM WHICH ARE DIRECTLY ABOVE THE PAIR OF POINTS ON SAID SKID-PAN ADJACENT TO THE POINT ON SAID SKID-PAN FROM WHICH THE PAIR OF STAYS EXTEND WHEREBY THE NUMBER OF SAID STAYS EQUALS THE TOTAL NUMBER OF SAID UPPER AND LOWER POINTS AND THE STAYS EXTENDING FROM EACH OF SAID LOWER POINTS CROSSES THE STAYS EXTENDING FROM TWO ADJACENT LOWER POINTS, SECURING MEANS FIXEDLY SECURING THE ENDS OF SAID STAYS TO SAID PLATFORM AND SKID-PAN AT ONE OF SAID UPPER POINTS AND ONE OF SAID LOWER POINTS, SHOCK ABSORBING MEANS EXTENDING BETWEEN SAID CENTRAL AREAS OF SAID PLATFORM AND SAID SKID-PAN, SAID SHOCK ABSORBING MEANS BEING COMPLETELY SURROUNDED BY AND ENCLOSED BY SAID STAYS, SAID POINTS BEING ARRANGED SO THAT EACH OF SAID STAYS FORMS A RELATIVELY SMALL ANGLE WITH SAID PLATFORM. 